There are many aspects of the natural history of HPV infection of the genital tract that remain poorly understood. Estimates of the prevalence of HPV infection have been based on the detection of viral nucleic acids in samples from various anogenital sites. We have developed serologic assays using bacterially expressed fusion proteins and synthetic peptides which are capable of measuring human serum antibodies to HPV 6 and 16 in a type or "serotype" specific fashion. The overall goal of this project is to obtain data about the humoral immune response to HPV infection. The specific aims are: 1) to determine the prevalence of HPV 6 and 16 antibodies in mothers and their children, and in young adults initiating sexual activity; 2) to determine whether there is a characteristic or sequential response to various viral antigens, and determine whether the serological profile can be correlated with the clinical status; and 3) to determine what biological role the humoral antibodies play in modulating HPV infection, using in vitro models.